Related topics: volcanic ash · earthquake · nasa · satellite · glaciers

Health fears as killer DR Congo volcano spouts ash

The DR Congo's Nyirangongo volcano has released large amounts of ash some two months after its eruption, sparking concerns for local residents' health, experts said on Sunday.

Like a molten pancake: A new model for shield volcano eruption

There are some large shield volcanoes in the world's oceans where the lava is usually not ejected from the crater in violent explosions, but flows slowly out of the ground from long fissures. In the recent eruption of the ...

Philippine volcano belches dark plume, villagers evacuated

A small volcano near the Philippine capital belched a dark plume of steam and ash into the sky in a brief explosion Thursday, prompting officials to start evacuating thousands of villagers from high-risk areas.

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Volcano

A volcano is an opening, or rupture, in a planet's surface or crust, which allows hot, molten rock, ash, and gases to escape from below the surface. Volcanic activity involving the extrusion of rock tends to form mountains or features like mountains over a period of time. The word volcano is derived from the name of Vulcano island off Sicily. In turn, it was named after Vulcan, the Roman god of fire.

Volcanoes are generally found where tectonic plates are diverging or converging. A mid-oceanic ridge, for example the Mid-Atlantic Ridge, has examples of volcanoes caused by divergent tectonic plates pulling apart; the Pacific Ring of Fire has examples of volcanoes caused by convergent tectonic plates coming together. By contrast, volcanoes are usually not created where two tectonic plates slide past one another. Volcanoes can also form where there is stretching and thinning of the Earth's crust (called "non-hotspot intraplate volcanism"), such as in the African Rift Valley, the Wells Gray-Clearwater volcanic field and the Rio Grande Rift in North America and the European Rhine Graben with its Eifel volcanoes.

Volcanoes can be caused by mantle plumes. These so-called hotspots, for example at Hawaii, can occur far from plate boundaries. Hotspot volcanoes are also found elsewhere in the solar system, especially on rocky planets and moons.

This text uses material from Wikipedia, licensed under CC BY-SA